'.\" t
.TH "clset" "1M" "Jun 20, 2006" "1\&.2\&.0"
.SH NAME
clset \- Change currently valid nodes for an application

.SH SYNOPSIS
.TS
l l.
clset	\fB--application|-A\fP \fIappname\fP [\fB--verbose|-A\fP]
	[\fB--nodes|-N\fP \fInode1[,node2]\fP] [\fB--nochecksums\fP]
.TE

.SH DESCRIPTION
\fIclset(1M)\fP is the utility that can run on either node in a \fBRUNNING\fP
cluster to alter the nodes that are considered valid for the specified 
application.

When the cluster is newly formed both nodes are considered suitable for all
applications defined. Of course the administrator may have defined a 'preferred
node' in the application configuration, but if the preferred was not available 
the application would still start [on the other node].

When a process monitor for an application notices a certain number of failures
in a configured threshold it will result in the application believing a 
\'software' failure has occured and fail-over the application to the alternative
node [assuming it is available]. When this occurs the cluster marks the 
previous node as 'unsuitable' for the application and will not fail-back the
application if a problem occurs on the new node.

This behaviour ensures that applications do not 'bounce around' the nodes in 
the cluster. However if the condition of the original node is fixed this 
condition needs to be reset. To achieve this the \fIclset(1M)\fP is used.

.SH OPTIONS
.TP
.B \-A,--application
Indicates the name of the application to reset the list of valid nodes
for. This is the only mandatory option.
.TP
.B \-V,--verbose
Verbose mode - show progress messages whilst performing changes.
.TP
.B \-N,--nodes
The comma-separated list of nodes that should now be considered valid
for the application. With Linuxha.net 1.x only one or two nodes can be
specified.

If the \fB--nodes\fP argument is not specified then the default action is 
to ensure that \fBboth\fP nodes are again valid to host the application in
question.
.TP
.B \--nochecksums
Normally if the cluster or application configuration files do not match the
expected checksums the command will abort. Specification of this argument
will override this behaviour.

.SH CAVEATS
Although the application and node details are validated little checking occurs]
beyond that. For example if an application is running on node 'n1' and the
administrator defines the only valid node for that application is 'n2' the 
application will continue to run on 'n1' - it does not suddently fail-over
to 'n2' - which some people may consider a bug [but is not].

This tool only records the information on a transitory basis. Halting the
cluster will ensure that when it is reformed both nodes again will be 
considered as suitable for hosting the application.

.SH EXIT CODES
The utility supports the following return codes;

.TP
.B 0
The specified action was completed successfully - the message "OK" [the response
from the cluster daemon] - will be shown on the command line.
.TP
.B >0
An error has occured - a message on the Standard Error channel will describe
the reason for the failure.

.SH SEE ALSO
.TS
l l.
lemsctl(1M)	- Communicate with Lems Daemon
cldaemonctl(1M)	- Communicate with Cluster Daemon
clhbdctl(1M)	- Communicate with Cluster Heartbeat Daemon
clnetctl(1M)	- Communicate with Cluster Network Daemon
.TE

.SH AUTHOR
Simon Edwards, simon.edwards@linuxha.net - http://www.linuxha.net
